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Patented Jan. 8, 1929.

UNITED STATES PATENT! OFFICE.

HANS T. CLARKE AND CARL J. MALM, OF ROCHESTER, NEW YORK,. ASSIGNORS TOEAST- MAN KODAK COMPANY, OF ROCHESTER, NEWYORK, A CORPORATION OF NEWYORK.

PROCESS OF MAKING CELLULOSE ACETO ESTERS CONTAINING HIGHER ACYL GROUPS.

NoDrawing.

This invention relates to processes of making cellulose aceto esterscontaining higher cellulose acetates can be esterified in this Way witha surprisingly wide variety of acyl groups. Suitable anhydrides whichimpel the esterification, can be either those which themselves containthe higher 'acyl groups, or those which do not contain such groups butimpel esterification when mixed with acids.

- containing said higher groups.

We shall now give numerous examples of different ways in which ourinvention may be carried out, but it will be understood that the latteris not limited to the details thus given, except as indicated in theappended claims.

We preferably employ acetone-soluble cellulose acetates containing from34.5% to 37.5% of acetyl. These are substantially undegraded asindicated b their ability to form flexible, transparent ms from theirsolutions. They are hydrolyzed cellulose acetates, the original acetylpercentage having been above 43% but lowered when deacetylationtookplace during hydrolysis. Of course, deacetylated cellulose acetateshaving acetyl values outside of the range hereinabove given can beutilized, but those described are commercially-valuable andsatisfactory.

- Five parts by weight of such a cellulose acetate are added to anesterifying mixture comprising 20 parts by wei ht of stearicanhydrideand 40 parts by weight of chloroacetic acid. Any of thew'ell known esterifymg catalysts can be employed, but magnesium perchlorate, say .05parts by weight is as convenient as any. The reaction mass thus.obtained iskept at Q0 to C. for about four hours. The product can beisolated from the Application filed law 18, 1928. Serial- Ro. 248,741.

.anhydride, there can be substituted an equimolecularamount of ananhydride of one or more of the followin organic acids,proplonic,n-butyric, 1soutync, n-va leric,'isovaleric, n-heptylic,'lauric,myristic, palmitic,

cyclohexanecarboxylic, crotonic, cinnamic,

hydrocinnamic, undecylenic, o-methoxybenzoic, benzoic. i

In another example of our. invention, 5 parts by weight of ydrolyzedacetone-soluble cellulose acetate containing about 36.6% of acetyl areadded to an esterifying mixture containing 15 parts by weight of stearicacid, 20 parts by weight of chloroacetic anhydride, 20 parts by weightof chloroacetic' acid, and .05 parts by weight of magnesium perchlorate.The mixture is maintained at'60 to 65 for about four hours, the productbeing precipitated with agitation into warm methyl alcohol. After washinwith the latter, the

- precipitate can be disso ved in acetone, from which solution it yieldstransparent, flexible films. The precipitate contains about 45.7% ofstearyl.

In the last given example, there can be substituted in place of stearlcacid an equimolecular proportion of one or more of the followingacids,'propionic, n-butyric, iso-butyric, n-valeric, iso-valeric,n-caproic, n-heptylic, caprylic, pelargonic, capric, lauric, myristic,palmitic, crotonic, oyclohexanecarboxylic, benzoic, o-methoxy-benzoic,0'-chloro-benzoic, acetyl salicylic, phenylacetic, hydrocinnamic,cinnamic. The chloroacetic anhydride is a typical and preferred exampleof an organic and anhydride which impels esterification, but is freefromcellulose-esterifying groups.

During the'esterification, it is converted into chloroacetic acid whichis also free from cellulose-esterifying groups under the conditionshereinabove specified. Other organic acid anh drides havin the same.general charactenstic' are the ha ogenated fatty acid anhydridescontaining less than .10 carbon atoms,-such as di and trichlor aceticanhydrides, mono, di and tribrom acetic anhydrides, mono, di andtrichlor, and brom propionic and butyric anhydrides. But halogenzvmagnesium perchlorate. The mixture is kept at 65 C. for about fourhours. It is then precipitated with agitation into methyl alcohol, andthe precipitate washed with the latter. The product is soluble inchloroform or acetone, and may be deposited from such solutions in theform of transparent, flexible films. The cellulose aceto-oleate thusproduced contains an ethylenic double bond in the longroleic chain. Thiscan be halogenated. or example, the washed precipitate is-dissolved in15 parts by weight of chloroform containing 2 parts by Weight ofbromine. After about an hour at room temperature, the mixture beingoccasionally agitated, the solution is precipitated into methyl alcoholand the precipitate washed with the latter. The product contains about15.7% of bromine, is soluble in acetone, and from its solution in thelatter yields flexible, transparent films, theinflammability of which isremarkably low. Other unsaturated acids of the acrylic seriescan besubstituted, in equimolecular proportions, for oleic acid, such ascrotonic, and undecylenic.

By carrying out the last given example with hydrolyzed acetone-solublecellulose acetate containing 34.5% of acetyl, there is obtained a finalcellulose aceto-dibromo stearate containin about 19% of bromine.

In anot 'er example, 5 parts by weight of partially deacetylatedcellulose acetate containin 37.5% of acet l are added to a mixtu-re o 20parts by weight of chloroacetic anhydride, and 40 parts by weight ofchloroacetic acid. When all of the ingredients have entered-intosolution, there are then added to the mixture20 parts by weight of 9-1Odibromo stearic acid and .05 parts of magneslum perchlorate trihydrate.This mixture is kept at to C. for about four hours. The precipitatingand washing are carried out in methyl alcohol. The cellu-' 'loseaceto-dibromo stearate thus obtained,

may be increased to 19.5% by starting with an acetyl cellulosecontaining 34.5% of acetyl. I

If, in the immediately preceding example, 9-10dichloro" stearic acid besubstituted for the dibromo stearic acid, there will be obtainedcorresponding cellulose aceto-dichloro,

stearates, containing from 7.3% to 9.6% of chlorine, depending upon thereceptivity of the particular hydrolyzed cellulose acetate employed.Also, if tetrachloro stearic acid be substituted for dibromo stearicacid in said example, there will be obtained cellulose aceto-tetrachloro stearates containing from 20% to 23% of chlorine. These aresoluble in acetone and yield flexible films.

It will be noted that in our process, strong mineral acid is notliberated. When acyl chlorides, instead of anhydrides, are used incellulosic esterification, the liberated hydrochloric acid isdestructive'to apparatus and tends to rapidly degrade the celluloseester.

So far as we are aware, acyl chlorides have, .therefore, not been usedcommerclally for cellulosic esterification, and it is a fundamentaladvantage of our rocess that it depends upon anhydrides whlch do notproduce objectionable or degrading by-products and can be handled in theplant in substantially the same way as acetic anhydride, With which theart is familiar in commercial practice.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent is:

1. In the process of making cellulosic aceto esters containing higheracyl groups, treating partially deacetylated cellulose acetate with anesterifying mixture which includes an organic acid anhydride of highermolecu lar weight'thanaceticanhydride and impels esterification, therebeing in said mixture a source of said higher acyl groups.

2. In the process of making cellulosic aceto esters containing higheracyl groups, treating partially deacetylated cellulose acetate with anesterifying mixture which includes an organic acid anhydride whichimpels esterification but is free from cellulose esterifying groups andduring the e'sterification is convertedinto a compound thatis also freefrom cellulose esterifying groups, there being in said mixture anorganic acid containing said higher groups.

3. In the process of making cellulosic aceto esters containin higheracyl groups, treat- "ing acetone-solu 1e .hydrolyzed cellulose acetatewith anesterifying bath which incllides a halogen'substituted fatty acidanhydride having less than 10 carbon atoms, there being in said bath anorganic acid containing said higher groups.

4. In the process of making cellulosic aceto esters containin higheracyl groups, treating acetone-solu le hydrolyzed cellulose acetate withan esterifying bath which includes chloro-a'cet-ic anhydride and amonocarboxincludes chloroacetie anhydride and oleic ylic organic acidcontaining said higher acid. v v groups, the latter having an ethylenicdouble Signed at Rochester, New York this 10th 1 bond therein. day ofJanuary 1928.

5 5. In the rocess of making cellulose aeebo oleate',treatmgpartially'deacetylated cellu- HANS TL CLARKE. lose acetate withan esterifying bath which CARL J. MALM.

H CERTIFICATE OF CORRECTION. melt n 1,698,048, GrantedJannary-S, 1929,m.

' I HANS T. CLARKE ETAL.

' It is hereby certified-that error ippears in the above numbered patentrequiring correction as follows: In theheading to the printedspecification, M6, for serial "No. 248, 74l"read "No. 247,741"; and thatthe said Letters Patent should be read with this correctiontherein thatthe same may conform to the record of the case in the Patent Office.

Signed and sealed this 4th day of February,-A. D. 1930.

M. J. Moore, I (Sell) Acting Commissioner of Patents.

